Safety device for scaffolding



-C. A. LUNDGREN.

SAFETY DEVICE FOR SCAFFOLDING.

APPLICATION FILED FEB. 23| 192|.

Patented Apr. 11, 1922.

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C. A. LUNDGREN.

SAFEIIY DEVICE FOR SCAFFOLDING.

APPLICATION FILED FEB. 23| 192|. 1,412,624. Patented Apr. 11, v1922.

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PATENT OFFICE.

CARL A. LUNDGREN, OF CHICAGO, ILLINOIS.

Application filed February 23, 1921.

To @ZZ whomy it may concern Be it known that I, CARL A. LUNDGREN, a citizen of the UnitedStates, residing at Chicago, in the county of Cook and State of linois, have invented certain new and useful Improvements in Safety Devices for Scaffolding, of which the following is a specification.

This invention relates to safety devices but more particularly to safety attachments for use with scaffolding, and has for its primary object to provide a simple and eflicient device for preventing the falling of the scaffolding in case the usual hoisting tackle breaks or becomes accidentally released.

Particularly in the cleaning of masonry Vbuildings chemicals'are used which destroy or materially weaken the usual supporting ropes without this weakness being evident to the workmen using the scaffolding. Accidents due to the falling of scaffolding are frequent and quite generally result fatally.

Further objects of the invention are to provide a safety device which is normally engaged or locked but which may be easily disengaged to permit the scaffolding to be raised or lowered and which automatically reengages when the disengaging means is released, and in general to provide an improved safety device for scaffolding.

The many other objects and advantages of the invention will be'better understood by reference to the following specification when considered in connection with the accompanying drawings illustrating a selected embodimentthereof, in which Fig. 1 is a side elevation of the invention complete.

' Fig. 2 is an end elevation.

Fig. 3 is an enlarged plan view of the safety lock.

Fig. 4 is an enlarged side elevation of the lower hoisting block with the safety lock thereon, and

Fig. 5 is the same as Fig. 4, front elevation.

Referring to the drawings, the usual platform 10 is supported by a pair of bales 11 disposed substantially at opposite ends thereof and each connected to its respective lower block 12 of the hoisting tackle. The customary upper blocks 13 and hoisting ropes 14 are provided. The upper blocks are supported from the roof or cornice in the usual manner. As the hoisting tackle and Specication of Letters Patent.

SAFETY DEVICE FOR SCAFFOLDING.

Patented Apr. 11, 1922. serial No. 447,290.

the safety devices are substantially the same at each end of the platform, only one will be described hereinafter.

A safety cable 15 preferably of wire is suspended from the roof or cornice in substantially the same manner as the upper block 13. The safety lock is preferably carried by the lower block 12. This lock is mounted on a base-plate 16 which is secured upon the outer face 17 ofthe block by screws 18 or other suitable means. Parallel guides 19 are formed upon this plate. A bolt 20 has itshead 21 seated in the slot formed between these guides 19 and is retained therein by the inwardly turned flanges 22 of the guides. A member 23 has its inner end pivotally mounted on the bolt. A locking jaw 24 is formed on this member or secured thereto. A locking jaw 25 is pivotally mounted on the bolt 20 and disposed opposite to the jaw 24. A link 26 has its lower extremity pivotally mounted on the bolt 27 which passes through the block 12. The opposite end of this link 26 is pivotally connected to the 'outer extremity of the arm 27 on the vj aw 25 at 28. The outer end 29 of the member 23 is turned upwardly over the link 26. An eXtensible spring 30 connects this end 29 with the baseplate 16.y A cable retainingvplate 31 is pivot-ally mounted at one end on the bolt 20 and the opposite end thereof rests upon the outer face of the jaw 24. An eye bolt 32 mounted on the pin 33 in the slot 34 in the member 23 is adapted to be turned into the slot 35 in the plate 31 to retain the cable 15 between the jaws. A wing nut 36 on the bolt 32 retains this bolt within the slot 35.

The spring 30 acting through the member 29 normally retains the bolt 20 in its uppermost position and the jaws are closed upon the cable 15. Upward movement of this cable relative to the block 12, such as would occur if the hoisting rope should break or be released, would cause the jaws to more tightly grip the cable and stop such movement.

A control or lock releasing rope 37 is connected to the memberl 23. A downward pull on this rope causes the bolt 2O to be drawn downwardly between the guides. The downward movement of the bolt 20 causes the link 26 to rotate the jaw 25 on this bolt in a clockwise direction and releases the cable. While the lower end of the rope 37 may be is being manually operated.,

free, l have found it advantageous to secure vthis end to the bale ll in the mamier indicated in Fig. 2 so that this rope may be controlled by the foot wliile tlie hoisting tackle A pressure Vof the foot on this rope releases the safety lock, and permits the scaffolding to be raised or lowered by the tackle in the usual manner as long as the pressure on the rope is maintained. lVhen this pressure is withdrawn, the jaws will be instantly closed upon the cable by the spring in the manner described. The cable 15 may be withdrawn from the safety device by loosening the wing nut 36 and swinging the eye bolt out of the slot 35 in the plate 31. This permits the plate 3l to be .rotated upon the bolt 20.

it will thus be seen that with the present invention accidental failing of the scaffolding is rendered impossible. The locking yjaws normally engage tlie safety cable at Iall times and are only disengaged therefrom while the control rope is being pulled in the manner described. The form of the jaws is such that the gripping action increases proportionally with the No attention. need be paid to the safety meclianism except when thesca'lfolding is to be raised or lowered.

The safety device is simple and compact in structure and automatic in action. l am aware that many changes may be inade in the construction and arraiigemenitY of the parts without departing from the spirit of my invention and I reserve the righty to make all such as fairly fall within the scope of the following claims.

` I claim:

1.f ln a safety device for scaffolding, the combination witli'a platform, and supporting and hoisting tackle therefor, of an enieigency support, and meansI normally engagload on the scaffolding.V

iug said support to prevent relative movement of said platform and said support.

2. In a safety device for scaffolding, the

combination with a platform, and supporting and hoisting tackle therefor, of an einergency support, and a safety lock normally gripping said support to prevent movement of said platform longitudinally of said sup,- port.

8. In a safety device for scaffolding, the combination with a platform, and supporting and hoisting tackle therefor, of an emergency supporting cable, a safety lock normally gripping 'said' cable to prevent movement of said platform longitudinally of-said cable, and means for releasing said lock'to permit said platform to be raised or lowered by said tackle.

l.VK In a safety'device for scaffolding, the

Vcombination with a platform, and supporting andlioisting tackle therefor, of an emergency supporting cable, a safety lock normally engaging said cable to -prevent movement of said platform longitudinally of said cable, andnieans for disengaging'said lock to permit said platform to be raised'oi lowered, said lock'automatically reengaging as soon as said disengaging means is released.

5. A safety device for scaffolding, comprising anenicrgency supporting cable, jaws disposed on opposite sides of said cable and normally engaging said cable, land means for releasing said jaws from said cable.

n 6. A safety device for scaffolding, comprising an emergency supporting cable, jaws disposed on opposite sidesrof spring normally retaining said jaws in their engaged position,

and means for manually Y moving said jaws out of engagement with said cable.

CARL A. Lunneiinit. 

